Exam 2 Quiz 1 Flashcards
Population Ecology
The study of how and why population size, structure, and distribution patterns change over time
Population definition
a group of individuals of the same species in a particular area so they can potentially interact
*you potentially could interact with everyone here at Luther
Why study populations?
-to understand what factors affect/might be influencing population increase or decrease
-to make predictions about change in populations in the future
-effectively manage populations (wildlife) through hunting and fishing
Distribution
where are members of the population located?
Abundance
how many individuals are there in the population?
Range
the entire geographic area where members of a species are found
*affected by abiotic and biotic factors
-contains overexploitation, habitat loss, and extirpation
Biotic factors that affect bobcat range and therefore abundance and distribution?
1) food availability (PREY): squirrels in forests and rabbits in prairies
2) competition for space (territoriality)
Abiotic factors that affect bobcat range and therefore abundance and distribution?
1) snowfall- bobcats can’t walk on snow far North, lynx have adaptation of big feet and can
2) overexploitation
3)habitat loss
4) extirpation
some ovals hate Eli
Overexploitation
-over harvesting (bobcat fur in midwest)
-not enough being born to replace those killed
-need a sustainable population
Habitat Loss
conversion of forests and prairies in 1800’s to cropland of corn and soybeans ELIMINATED PREY
Extirpation
a localized extinction
-species exists in parts of range but extinct in others
Quantifying Abundance- How do we determine population size?
Census and Sampling
Census
count every individual in the population
-works well for small populations of organisms that are visible and easy to see
Sampling Def
a way to estimate population size of smaller animals that are hard to count, take samples
sample: a subgroup of a population
Types of Sampling
1) Mark-Recapture
2) Plots
3) Quadrants
4)Transects
Mark-Recapture Sampling
mark 100 bobcats, release them, capture 50, 10 of them are already marked, what’s the estimate size of the population?
Lincoln Index: N= Mxn/m
N- size of population
M- # marked initially
n- # of all individuals in 2nd sample
m= # of marked ind from 1st sample in 2nd sample
100x50/10 = 500
Plot Sampling
Used to sample large ares
ex: trees in HRW
-Center point and 8 m circle out from that to get 200 m2
Quadrant Sampling
used for smaller organisms in smaller areas, like plants in a 1m by 1m square
-let us calculate density, percent cover, and biomass
Demography
the study of how population changes over time, space, ect
Models
help is understand and describe change in a population
Population growth model
what affects population size?
births (natality) and immigration increase
deaths (mortality) and emigration decrease
EXPONENTIAL GROWTH
population growth model
dN/dt = rN (population growth rate)
N- number of ind in the population (pop size)
dN- d is the change and dN is the change in population size
t- time (min, sec, years)
dt- change in time
what is “r”? formula?
The per capita rate of increase (per capita means ‘for each ind in the pop’)
r=b-d
b=birthrate or number of births
d= death rate or number of deaths
r= number of individuals added to or subtracted from population per individual in population
r=0
population neither increasing or decreasing, stable